The 44-year-old man needed treatment at Scarborough Hospital following the assault outside The Albert pub on North Marine Road at 10.55pm on Saturday (July 28).
North Yorkshire Police has asked for help from the public to help them establish the full circumstances surrounding the incident, and the force is particularly keen for information about a man who was at the scene, who may be able assist the investigation.
The man in question is white, slim, 6ft and was aged between 40 and 60. He wore a blue and white polo shirt with blue jeans.
Anyone with information is asked to contact police on 101, quoting reference number 12180138693.